Enantioselective synthesis of dihydropyrazoles by formal [4+1] cycloaddition of in situ-derived azoalkenes and sulfur ylides

J Am Chem Soc. 2012 Apr 25;134(16):6924-7. doi: 10.1021/ja301196x. Epub 2012 Apr 17.

Abstract

An unprecedented strategy to access highly enantioenriched dihydropyrazoles is described. It involves formal [4+1] cycloadditions of in situ-derived azoalkenes and sulfur ylides catalyzed by a chiral copper/Tol-BINAP complex. A variety of synthetically and biologically important dihydropyrazoles have been obtained with high enantioselectivities (up to 97:3 er) in good yields (83-97%).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkenes / chemistry*
  • Azo Compounds / chemistry*
  • Catalysis
  • Crystallography, X-Ray
  • Cyclization
  • Models, Molecular
  • Molecular Structure
  • Organometallic Compounds / chemistry
  • Pyrazoles / chemical synthesis*
  • Pyrazoles / chemistry
  • Stereoisomerism
  • Sulfur / chemistry*

Substances

  • Alkenes
  • Azo Compounds
  • Organometallic Compounds
  • Pyrazoles
  • Sulfur